Profile of political party activists 2 A psycho-political profile of moderates and left-wing and right-wing extremists Abstract.The present study tests for differences among samples of activists from moderate and extreme political ideologies. Previous studies comparing ideological groups have been restricted to tests of betweengroup differences in the means of relevant political psychological variables, thereby neglecting eventual group differences in the variances, meanings and nomological networks of the tested variables (i.e., their psychometric properties, the pattern of correlations among these measures, and the presence of mediation and moderator effects). A first exploratory study used data from the European Social Survey (total N = 7314) comparing groups of political party members on the basis of their scores on a selfplacement left-right scale. The second study (total N = 69) constituted an in-depth test for the presence of differences between samples of political activists of moderate parties, communists, anarchists, and right-wing extremists. The present results revealed that there is a fair amount of heterogeneity within left-wing and right-wing extremists, indicating a substantial amount of within-group variance of social attitudes, values, and prejudice. Moreover, the extremist ideologies are best approached as distinct ideologies that cannot be reduced to extreme versions of moderate ideology, and differences in the meanings and nomological networks of the various extremist ideologies were also obtained. It is erroneous to consider members of extremist groups as being ‗all alike'. Moreover, the findings obtained in samples of political moderates do not seem to be a particularly solid basis for theories about extremism. We also present psycho-political profiles of communists, anarchists and right-wing extremists.KEY WORDS: anarchism; authoritarianism; communism; European Social Survey; extremism; ideology; values; right-wing ideology Profile of political party activists 3 What does it mean to be an ‗extremist'? Dictionary.com defines an extremist as a person who goes to extremes, especially in political matters, or someone who is a supporter or advocate of extreme doctrines or practices. In the present studies, we tightly stick to this definition, by investigating people who locate themselves on the extremes of a political left-right self-placement scale, and we studied members of extreme doctrines (i.e., anarchism, communism, and extreme rightists) as well. We believe it is of utmost importance to stress that specific political ideas should be considered within their specific cultural-historical time-space or context. Some ideas may be considered ‗very extreme' in one context, while these ideas may be very ‗moderate' in another context. As Sidanius (1985) has put it: -… belief in political and social equality of Blacks would most certainly have been a very ‗extreme' idea in the America of 1776 and is now becoming a very moderate idea in the America of 1984‖ (p. 639). According to the same logic, m...